[8] Bullous pemphigoid (BP) is a rare and chronic autoimmune disorder characterised by large sub-epidermal blisters called bullae that predominantly involves the skin and less commonly the mucous membranes.

Primary lesions of small and large blisters, known as vesicles and bullae, are found on the skin and sometimes on the mucous membranes.

[11] The bullous stage of BP shows vesicles and bulla, appearing on apparently normal or erythematous skin, predominantly at the flexural aspects of the extremities and the lower trunk.

The blisters are tense, about 1–4 cm in diameter, leaving eroded and crusted areas, together with urticarial and infiltrated papules and plaques in an annular or figurate pattern.

[13] Most bullous pemphigoid cases are due to autoantibodies (mostly IgG) directed at antigens (BP180 and BP230) arranged at the dermal-epidermal junction.

In the immunologic component, autoantibodies act against the hemidesmosomal bullous pemphigoid antigens BP230 (BPAg1) and BP180 (BPAg2 or type XVII collagen), located in the lamina lucida of the basement membrane zone.

[14] When the autoantibodies bind specifically to the target antigens, the complement system and mast cells are activated, representing the inflammatory component.

DIF of bullous pemphigoid will show the presence of fine, continuous and linear deposits of IgG and/or C3 along the epidermal basement membrane.

[13] Indirect immunofluorescence is used to detect circulating antibodies targeting the antigens at the basement membrane zone in patients with pemphigoid.

In bullous pemphigoid, circulating IgG targeting the basement membrane, mainly BP180 and BP230 hemidesmosomal proteins are detectable in 60-80% of patients.

Other drugs and immunomodulatory therapies are often used as adjunct to minimize the adverse effect of long term use of corticosteroids and improve the healing of the disease.

Studies have shown that patients with extensive bullous pemphigoid (defined as >10 new bullae per day) treated with topical corticosteroids (Topical Clobetasol Propionate 0.05% cream) had better clinical outcomes than patients with extensive bullae pemphigoid who were treated with systemic glucocorticoid therapy (Prednisone).

Should the patient develop flare up of the lesion, the dose should be increased to the previous level or higher and maintained longer before further, slower tapering.

[33] As MMP may lead to serious complications such as blindness and airway compression, early and aggressive treatment initiation may be needed.

Reticulated, white striations representing mucosal fibrosis often are present at sites of healed lesions, and functional limitations secondary to scarring may occur.

[14] Most commonly affecting the mouth, including the buccal mucosa, gingiva, tongue, vermillion lips, and palate.

Initially presented with unilateral conjunctivitis (such as burning or excessive tearing), then fibrosis beneath the conjunctival epithelium.

[14] Although not exclusive to laminin 332 MPP, the detection of antibodies bound to the dermal side of basement membrane zone-split (salt-split) skin suggests the possibility of this diagnosis.

Until definitive testing for laminin 332 antibodies becomes available, we recommend that patients with MMP in whom serum indirect immunofluorescence (IIF) studies reveal antibodies bound to the dermal side of basement membrane zone-split skin undergo age and gender appropriate cancer screening.

[14] Additional evaluation for malignancy should be performed as indicated based upon a review of symptoms, physical examination, and the results of age-appropriate screening.

Additional findings include sub-epidermal fibrosis which is consistent with the scarring nature of mucous membrane pemphigoid in older lesions and plasma cell infiltration.

Indirect immunofluorescence is used to detect circulating antibodies targeting the antigens at the basement membrane zone in patients with pemphigoid.

To increase the likelihood of detecting circulating antibodies, human basement membrane zone-split skin and/or concentrated serum should be used.

The factors that determine the type of therapy used for mucous membrane pemphigoid are: [1] site(s) of involvement, [2] severity of disease, [3] rate of progression.

Dental tray can also be fabricated to help in the application of topical steroids to lesional sites under occlusion for patients with gingival involvement.

For moderate to severe disease (including the ones involving ocular, nasopharyngeal, or anogenital mucosa) and patient who did not respond to local therapy adequately, systemic agents should be used.

[37] Whereas for systemic corticosteroids, 0.25 to 0.5 mg/kg of prednisolone is prescribed per day (twice-daily dosage is used during the acute stage and change to a single daily morning dose after new blister formation stops).

Thereafter, the dosage of prednisolone is slowly tapered over the months in combination with topical therapy or glucocorticoid-sparing agent (e.g., dapsone, azathioprine).

[51] Before meals, patients are advised to rinse with hydrogen peroxide (diluted with water to a concentration of 1:4 or 1:6) and diphenhydramine to reduce the pain.

[52] There is no known racial or geographic predilection, but several studies have suggested that there is an association of specific immunogenetic haplotype HLA-DQB1*0301 with MMP.